Adjustable thermostat



Jan. 25, 1949. J. L. scHwARTz ADJUSTABLE THERMOSTAT 3 Sheets-Sheet l Filed Aug. 2l, 1945 Jan. v25, 1949. J. L. SCHWARTZ ADJUSTABLE THERMOSTAT Filed Aug. 21, 1945 3 Sheets-Sheet 2 ccccctwm Jan. 25, 1949. J. L. scHwAR-rz ADJUSTABLE THERMOSTAT 3 Sheets-Sheet 3 Filed Aug. 2l, 1945 HIIHIIIII IIIIHII H U u H HIIIIIHU. IllnHHlllllknnY Patentedansiim ADJUSTABLE THERMOSTAT John Leonard Schwartz. Philadelphia, Pa., assignor, by mesne assignments, to The Philadelphia Thermometer Company, Philadelphia, Pa., a partnership comprised of J. Leonard Schwartz and Hugo Engelhardt Application August 21, 1945, Serial No. 611,819

This invention relates to adjustable thermostats, and particularly to devices controlling the closing of an electric circuit as a result of the expansion of mercury in a glass bulb, at a temperature which is predeterminedly variable.

In the prior art of such thermostats many efforts have been made to provide an adjustably positioned electrode moving in a packing gland or the like, but as these are never vacuum-tight, the devices are purely theoretical and for all practical considerations are inoperative. In the relatively few devices in which the operating parts are enclosed in a vacuum-tight disposition to the mercury column, the glass blowing problems connected with the manufacture have been so complex as to militate against commercial production, and moreover the operation of the adjustable electrode has been in many cases uncertain, subject to change under conditions of vibration, and of very limited range. Additionally, the marking of the devices for the point of desired temperature has been difficult and in many cases inaccurate. In many instances glass rupturing amalgamation of electrode and mercury has been accelerated by the necessary location of the electrodes in proximity to the bulb and exposure thereof to the heat of the bath incident upon the bulb. Finally, such prior devices have been cumbersome, possessed of strains which are incapable of relief, and are, therefore, delicate and incapable of use Where frangibility is a hazard.

It is among the objects of this invention: to provide improvements in the art of adjustable thermostats of the thermometer type; to obviate the disadvantages of the prior art adjustable thermostats; to provide a thermometer type adjustable thermostat in which the working elements are preformed separately from the glass in which they are ultimately enclosed prior to evacuation of the glass portion; to provide an adjustable thermostat with a double bore column, in one bore of which the adjustable or working electrode is movable to varying contact with mercury movable in the bore from the bulb and the other bore of which receives a common electrode and contains mercury contacting same and which forms the common return; to provide an adjustable thermostat of the thermometer type in which the column leading from the mercury bulb has no encasing shell and which therefore avoids the thermal lag attaching to prior art devices; to provide an adjustable thermostat in which fractional degree adjustments can be obtained; to provide a micrometric adjustment for the electrode of an adjustable thermostat; to provide an adjustable thermostat of the thermometer type which minimizes and simplifies glass blowing techniques; to provide an adjustable thermostat with a column having a double 26 Claims. (Cl. 20D-141) bore leading to an enlargement in which there is a partition to form centering means for the adjustable and fixed electrode elements, and also, when required, which forms a pocket for a reserve supply of mercury to be used when changes of setting are to be made; to provide a thermometer type of adjustable thermostat by which calibration is simplified and rendered more accurate than has previously been thought possible; to provide an adjustable thermostat of extreme sensitivity; to provide an adjustable thermostat so arranged that the common electrode is remote from the mercury bulb to minimize the effects of the hot bath thereon; to provide an adjustable thermostat in which amalgamation of electrodes is minimized; and other objects and advantages will become more apparent as the description proceeds.

In the accompanying drawings forming part of this description:

Fig. l represents a transverse vertical section through one form of adjustable thermostat according to the invention, partially in elevation.

Fig. 2 represents a fragmentary enlarged section of the upper end of the thermostat of Fig. i, taken on line 2--2 of Fig. 6.

Figs. 3 and 4 represent respectively horizontal sections through the thermostat taken on lines 3-3 and l-l respectively of Fig. 2.

Fig. 5 represents a fragmentary perspective of the preformed adjustment device of the invention according to the disclosure of Fig. 2.

Fig. 6 represents a fragmentary vertical section partially in elevation of the upper end of an adjustable thermostat taken on line 6-6 of Fig. 2.

Fig. 7 represents a side elevation, partially in section, of an assembled adjustable thermostat in a protective housing according to one form thereof.

Fig. 8 represents a fragmentary enlarged vertical section. partially in elevation of a modified form of adjustment mechanism.

Fig. 9 represents a fragmentary enlarged transverse vertical section of the modified form of adjustment mechanism of Fig. 8, taken on line 9 9 thereof.

Figs. 10 and 11 respectively represent transverse horizontal sections of the modified form of adjustment taken on lines lli-l0 and II-Il respectively, of Fig. 9.

Fig. 12 represents a vertical transverse section lthrough the double bore column and the mercury bulb, showing a modied form of common electrode disposition remote from the vicinity of the bulb to minimize amalgamation thereof with the mercury conductor.

Fig. 13 represents a fragmentary perspective partially in section of the adjustment according 3 to the modified form in the glass housing thereof and showing calibrations on the housing.

Fig. l4'represents a fragmentary enlarged perspective of the double bore column of Fig. l2, showing calibrations on the column.

Fig. 15 represents a fragmentary elevation of the annular magnet used to actuate the adjusting mechanism of either form of thermostat disclosed, showing the calibrations forsame relative to a datum line on the fragmentary elevation of the stationary housing.

In carrying out the invention in a preferred embodiment, an arrangement of threaded shank and traveling nut is provided and a working electrode is carried and adjusted in setting by the nut,

. v'and this is disposed inaglass housing. Anarma- -ture is provided internally of the housing for actuating the shaft in accordance with the rotations of an externally mounted annular magnet,

land a double bore glass column is provided, one

bore of which communicates with the bulb of mercury and the glass housing and the movable or working electrode travels in this bore to make and break contact with the mercury in the bore.

-The other bore forms a receiver for a common electrode as a common return and is in contact with the mercury bulb either directly or indirectly through the second bore, or through a cross connection t the rst bore. s

Referring to Figs. l, 2, 3, 4, 5, 6 and 7, the thermostat i0, at the lower end, has a mercury bulb II in direct communication with a working bore I2 of a double bored column i3. In this embodiment of the invention a short transverse embedded wire connector I4 is fused into the glass of the column I3, and extends from the mercury in the bore I2 to the mercury in the common bore I5 of the double bore column. As shown in Fig. 14 in detail, the column I3 is'preferably formed with an arcuate shield of white, as at lembedded and fused into or on the column itself and which is of such arcuate length and disposition as to shield the common bore I5 from view of the observer, while permitting the working bore I2 to be observed from a proper angle outside of the column. In one form of calibration of the instrument, the column I3 itself is graduated externally in lines II viewable against the background of the working bore, and of the electrode working therein, to be described. It

will be observed that the mercury bulb II containing the mercury I8, and the double bored column I3 leading to it, are not housed by any additional glass housing or other shielding element so that when immersed in a hot bath the reactions of the expanding mercury in the bulb and column bore I2 are fast and free from inertial lag.

At the upper end oi the column I3 a single slightly enlarged glass tube or housing 20 is fused, which is of such internal diameter and so arranged as to receive the metallic adjusting and supporting mechanism to be described. The upper end of the enlarged compartment defined by housing tube 20 is initially left open to receive the inserted assembly, to be described, and is arranged to be subsequently evacuated and the upper end fused shut in the completion of the instrument, as will be' described. The merely slightly enlarged housing tube 20 and the upper end of the column I3 are provided with a median glass partition 2| extending diametrically completely across the lower end of the tube 20, and fused into the end of column I3 and into the wall oi' housing 2Il to form with the convergent walls 22 and 23 or the housing 2li generally funnel side Where they are formed by the sides of the relatively fiat partition, and are rounded in the remainder of their peripheries. Pocket 24 forms a reservoir for receiving and storing mercury as a reservoir from which to restore mercury to the working bore, while pocket 25, in addition to forming a funnel for adding mercury to the working bore, also serves as a relief for mercury that may be extruded by excess heat and consequent expansion of the mercury from the working bore I2. Pocket 2li is used as a reservoir, as noted,

.from which the mercury can be moved by tilting the instrument to cause it to leave the pocket 24 to run into the chamber formed by the housing tube 2d, after which the device can be rotated while tilted to place the pocket 25 downwardly, then the device can be restored to a vertical position and the mercury initially in the reservoir 24 will be disposed in the pocket funnel device 25. Excess mercury from bore I5, on the other hand, can be moved into the storage reservoir 2d by a reversal of this procedure. The provision of the double bore tube facilitates the formation of the partition 2i between the bores, and insures the exact symmetrical centering of the latter. As the partition also serves as a supporting and centering device for the electrode adjustment mechanism, this symmetrical disposition, While not essential, is preferred, and is of importance.

In the form of adjusting mechanism shown in the recited figures, a tube 2B, formed, for instance, of stainless steel, or the like, is longitudinally slotted as at 21, and at the lower end is provided with an inset thrust bearing 28, into the opening of which the bearing stud element 30 of a threaded shank or shaft 3l is relatively dropped. The shaft is held against vertical retraction in the tube by an upper bearing member 32, and the shank is rotatable in the bearings in fixed concentric disposition ln the tube. At its upper end the threaded shank 3i is continued beyond the upper bearing 32, in a shaft 34 upon the subsequently attached preferably enlarged head 35 of which the winged armature 36 is anchored. 'l'his latter may be of any desired construction but for cheapness and emciency preferably comprises a single piece of sheet material of ferrous nature, so as to proyide a central relatively planar portion 3l extending on each side of a central grooved portion 33 having a complemental gripping portion 40 embracing the enlarged head so that the planar portion is diametrical of the enlarged head, with oppositely directed generally arcuate wing elements 4I and 42 at the outer ends of planar portion 3l. The armature is arranged to turn with a sumcient degnee of clearance relative to the inner surface of the housing tube 20, while still being within the range of the magnetic flux of the magnet to be described. when the assembly is properly disposed in the glass housing20. To secure such accurate disposition, the lower end of the tube 26 has' four radially extending arms secured to the tube, and preferably comprising integral prolongations thereof, respectively designated as 43, 64, 45 and 4 I6, and of such length as to center the lower end tween pairs of arms, as at 41, arranged to receive the upper end of the glass partition 2| The upper end of the metal tube 26 has a similar series of radial arms respectively designated as 46, 50, 5I and 52, and arranged in longitudinal axial alignment respectively with the lower arms.

Between a complemental pair of arms, such, for instance, as lower arm 46 and upper arm 52, there extends a permanently open glass tube 53 of small bore fused over laterally at the ends to anchor it in the arms, and which serves as an insulating guide for a common electrode, to be described. Upper arm 50 serves as a terminal for the grounding of the metal tube assembly by a lead 49 in electrical contact with the working electrode, to be described.

A traveling nut 54 is provided, having a lateral extension 55, guided and held against rotation in the slot 21 of the tube 26, threaded upon the shaft 3I and arranged to travel vertically as the shaft is rotated. The outer end of the extension 55 carries the elongated thin fairly stiff metallic electrode 59, which in final position extends downwardly between the lower arms 44 and 45, through the funnel-like pocket 25 and into the bore I2 in which itis vertically adjustable.

The assembly as described is dropped into the open upper end of the glass tube 20, guided by the respective arms of the metal tube, until slot 41 thereof seats upon the glass partition 2|. At this juncture the glass of housing 20 just above the respective upper arms 43 to 52 respectively preferably is softened by heat, and a slight indentation is made therein, forming a small abutment of glass -in the housing wall overlying and preventing axial movement of the upper arms and therefore of fixed portions of the entire unit. The common ground wire or connector 49 extending out of the top of the unit is preferably fused longitudinally into the wall of housing 20, for insulating same, and is then brought through and fused into sealing disposition in the glass wall adjacent the upper end of the glass housing 20, and is connected externally to a conducting annulus 54 disposed in a groove 55 toward the end of the glass housing. A common electrode 56 comprising a long relatively stiff thin metallic Wire, is threaded through the glass insulating guide 53 and through the pocket 24 beside the partition 2l to enter into the common bore I5, where it remains permanently in electrical contact with mercury in said common bore, and in the form shown in the recited figures, through the lower transverse connection I4, with the mercury I6 in bore I2. The upper end of the common electrode 56 is then lead to and fused into the upper end of the glass tube 20, for insulating same and passes through the wall of the housing in sealed relation and is connect-ed to the external annular conductor 51 received in another groove 58 formed adjacent to the glass tube end. Then the entire chamber is evacuated and the end of the tube sealed off under vacuum, as by the tip 60. Alternatively, the tube may be evacuated of air and then llled with an inert gas such as hydrogen or nitrogen under pressure, to minimize oxidation of the mercury.

In the preferred embodiments of the invention, the respective annular connectors 54 and 51 engaged in their respective grooves, are in electrical engagement with short connectors respectively 6I and 62 leading to terminals 63 and 64 on the end surface 65 of an insulating plastic mass 66 entirely surrounding the short connectors and the constrlcted end of the glass tube 20, and anchoring the whole in a guarding housing sleeve, preferably of metal, as' 61. The housing, formed of brass or the like, terminates at the upper end just short of the upper end 65 of plastic mass 66, and is provided with diametrically oppositely disposed studs 68, for bayonet-joint coupling to a contactmaking coupling member 10, by which the unit can be supported. The latter has contact elements 1I and 12 forming terminals for connectors 13 and 14 to the relay or other circuit operated by the thermostat. The metal sleeve 61 forming an effectively integral part of the thermostat unit in one form is rather short and at the lower end terminates in an internally threaded enlargement 15 spaced from the glass tube 20. A short externally threaded sleeve 16 of a diameter closely hugging the glass tube 20 is threaded into the enlargement and has an annular lower flange 11 forming a seat for an annular magnet 18. The flange is preferably knurled on its outer periphery to facilitate manual tightening, to engage the magnet between the flange and the planar lower surface 8D of the enlargement 15, to hold the magnet in a given position of angular adjustment. The length of the assembly of housing sleeves and magnet is such as to dispose the armature 36 of the adjusting unit axially so as to expose it to the magnetic flux of the magnet. A slight loosening of the lower threaded sleeve 16 enables manual angular adjusting of the magnet to rotate the armature to move the working electrode vertically in the working bore, to vary the setting at which the expanding mercury establishes contact. After a new setting has been made, the magnet is held stationary while the threaded sleeve is turned to tighten upon the magnet and hold it against undesired change of angular position.

As is known of such magnets, it is possible to have several different polarities in its peripheral extent, and the magnetic flux is of such strength that the armature 36 is in effect practically geared* to the magnet and responds with an angular change of position to the minutest change of angular position of the magnet. By having a suitable ne pitch on the threaded shank 3| and the complemental traveling nut 5ft, an extremely minute change of vertical positioning of the working electrode is available, which can represent a small fraction of a degree, and this can be predetermined and controlled in a satisfactory manner. Illustratively, as shown in Fig. 15 the annular magnet is provided with a r series of vertically extending calibrations, as at 8I, at the upper edge of the magnet, passing successively under a vertical datum line 82, inscribed on the stationary enlargement 15. This convenience is facilitated by applying legends indicating the direction of relative movement of the magnet to secure a desired direction of vertical adjustment of the working electrode 59. Illustratively, small arrows indicate the direction of movement to secure relative raising or lowering of the working electrode, and the legends raise and lower are applied to the stationary part on the respective sides of the datum line 82. By such predetermined relationship micrometric adjustments of the working electrode are secured.

In the form of thermostat just described, the common bore i 5, is provided with a block 89 to keep it out of contact with the mercury I8 in the bulb II, and the bore is filled with mercury extending into the pocket 24 at the terminus of the common bore I5, and forming a globule of reserve mercury 53. The entire common bore is 7 lled with a continuation of the mercury globule down below the cross connection I4 and against the block 89. The common electrode extends well down into the mercury in the common bore. The calibrations I1 applied to the exterior of the column may be applied after the relation of the working electrode tothe column of mercury in the working bore has been established, and in this case it may not be necessary toprovide any reservoir globule of mercury in the pock'et 24. Usually, however, the calibrations will be applied and subsequently interpreted in the light of actual functioning of the device. n

The instrument will be suitably supported and connected through the couplings shown, to the relay or other instruments which are to be controlled, the magnet will be turned on its support to turn the armature and the threaded shaft in such direction as to dispose the free lower end of the working electrode opposite the proper calibration of the series I1 for the temperature at which the circuit is to -be closed. The instrument in use is -then placed in the bath or other heated medium and exposed to the varying heat thereof. When the predetermined heat is attained, through expansion of the mercury i8 in the bulb II, the ascending column of mercury I8 in the working bore I2 will touch the free end of the working electrode and a circuit will be closed or completed from the wire 13, contact 1I, terminal 63, short connector 6I, through the common electrode 56, through the mercury 83 in the common bore, through the cross connection I4 into the mercury column in the Working bore I2, through' the adjustable electrode wire 59, into the metallic assembly of the nut, shaft, metal tube and grounding wire 49, and through short connection 51 to terminal 64, contact 12 and wire 14.

The remainder of the electricall network is of no Such a situation may occur, for instance, if the lower end of the instrument is inserted too deeply into the bath so that the latter surrounds the column I3 above the cross connection I4 oi' the device so far described. This may cause a gradual increase of thickness of the cross connection I4 from amalgamation with the mercury in the common bore, or from the working bore, which in due course, by a sort of creeping action along the cross connection sets uP, internal strains by the enlarging cross connection, and rupture and destruction of the instrument may occur. Of course, in the normal proper use of the instrument. this hazard does not become effective, but it may be dilcult to insure proper use.

y As a modification that may well be'the preferred form of the invention, to minimize the chances of the previously discussed undue amalgamation, the structure shown in Fig. 12 is provided. In this form of device a double-bored column 92 is provided in which both the common bore 9d and the working bore 95 are in constant communication with the interior of the bulb 96. The common bore Se extends almost to the point of debouchrnent into the'enlargement. formed by the housing tube 2li. beside the partition 2i, where itis sealed transversely as at 9V. The mercury `I8 extends permanently from the bulb up into the common bore S4 to the transverse abutment 91 despite fluctuations in volume of the mercury in thebulb 9S. The column 93 contains a short pocket e@ in axial alignment` with the common bore 9d on the other side of the abutment 81, in which a globule of mercury ili is disposed and permanently held and the upper end of the pocket 98, is provided with a transverse abutment lili in which there is an aperture |02 to admit the downwardly pushed common electrode 56, extending through the opening |02 into the mercury in pocket 98 after passing may be heated to a point of forcing some mercury outwardly into the pocket 25, after which the instrument is inverted, and turned to cause the globule to pass on the other side of the partition te storage in the pocket 24, upon restoring the vertical position of the instrument. Conversely,

. if the amount of mercury is low in the working bore, additional mercury can be caused -to enter this bore from the storage globule, by reversing the inclination and rotation, and heating the bulb until the mercury then placed in the pocket 25 joins the column to form a solid column in the working bore I2 as it contracts.

It is to be observed that theinstrument as formed, is slim, and has no supplemental enclosing tubes of glass surrounding other tubes or columns, as for protecting a common electrode entering the bulb I I, as in prior devices, and that extremely fine and delicate adjustments can -be made for the circuit controlling temperatures.

Applicant has discovered that under certain conditions an amalgamation of the mercury with a connector wire or electrode occurs, which may ultimately be disruptive of the glass in which the wire is fused. Such a. condition may occur when the embedded wire is in more or less constant contact with mercury at such elevated temperatures that volatillzation of the mercury occurs.

through the relatively short upper bore it leading from the housing 20 in axial alignment with the pocket 88 and the common bore 84. A short wire 99 only long enough to establish a good electrical contact between the mercury in the common bore 94 and the mercury |00 in the pocket 98, is fused into the partition of abutment 91. The mercury lili) is preferably not of such volume as to completely illl the short bore 98, but is of such depth as to .establish good electrical contact with the end of the common electrode 56 when the latter has been pushed a suitable distance into the bore QB.

It will be observed that with this modied form the circuit is from outside of the instrument, through the common electrode 56, the mercury |00 in pocket 98, the wire St, and the mercury It in the common bore 94 and in the bulb 96, through the mercury in the working bore 95, and through the working electrode 59, and through the 'connections already described, out of the instrument. Note that the wire 99 is weil toward the upper end of the instrument `well K away from the direct or radiant heat of the bath and is therefore so disposed as to be relatively immune to the amalgamation that might attach to its disposition close to the bulb.

As a further\protection for the instrument either in the form just described or in the modifled form to be described, a metallic shield and f upper end by an insulating apertured plug 84 through which the lead wires for the instrument extend, as at 85 and 86 in the modified form of the upper end of the instrument shown, and the lower end is provided with a reduced portion 81 forming a downwardly presenting thrust shoulder 88, and upon which the annular magnet 18 is rotatably mounted. The sleeve 83 has an externally threaded portion 18 at its lower end below the reduced portion 81, and to this is 'threaded a longitudinally slotted cylindrical tube 80 in which the slot 8| forms a sight window for the double bore column i8. 'I'he protecting tube 80 is open at the lower end at 81 to enable the bath to enter the tube 80 to incidence upon the bulb and preferably the tube 80 carries the anchored supporting ange 82 by which the in strument is held in predeterminedly positioned vertical disposition in the bath.

It will be seen that within the broad purview of the invention, of entirely preformed actuating means insertable in the glass assembly, other forms of actuating devices and assemblies can be used. One such modified form is illustrated in Figs. 8, 9, l0, 11 and 13. In this form of the invention, in place of the concentrically disposed slotted tube of the previous forms, an eccentrically disposed backing plate is provided as at |03 and which at the upper end has angularly divergent, preferably integral, arms, comprising a long arm |04 having an aperture |05, and a pair of spaced short arms respectively |06 and |01, the ends of which are preferably curved to conform to the interior of the slightly enlarged glass tube housing 20. In this connection, it is to be understood that the glass structure is the same in both types of thermostats, except possibly for graduations, and the same reference characters attach to likeparts. Similarly the arms of the previously described form of actuating assembly will also preferably be curved to llt the housing tube 20. The short arm |06 of the instant form is apertured as -at |08 and a short glass tube l i as an insulating guide has one end fused over outwardly to anchor the tube in the arm |06. The outer ends ofthe arms |01 and |06 in one direction and of the long arm |04 in a diametrically Aopposite direction, have such .spacing as just to conform to the interior circumference of the glass tube 20. At thelower end of the plate |03 there are a' pair of spaced angularly divergent short arms, respectively Il and H2. in alignment respectively, with the resportive upper short arms |06 and |01, and arm i has an aperture H3 in which the lower end of the guiding insulating glass tube .H0 is received and fused to anchored relation.- The lower end of plate `"i3 third arm. aligned with and comprising a short above the lower short has an angula'rly bent the upper long arm |04, member I4 in a plane arms and H2, bent carrying the nut to 'in a vertical adjacent to and over 10 ranged so as to abut the against the partition.

A threaded shaft is provided having a reduced upper end |2| insertable though the aperture |05 in the upper arm |04 and forming a shoulder |22 for engagement beneath the said arm when inserted from below and at the lower end the shank is also reduced into a bearing ex tension |28 insertable through the aperture Ii'8 in the upper bent member H1, and forming a shoulderv |24 engaging the upper surface of member ||1. The threaded shank is thus disposed concentrically and symmetrically in the glass housing. A traveling nut |28 is provided having a flattened edge surface at |26 arranged for substantially parallel juxtapositlonlng relative to the at plate |03 to prevent the nut from turning with the shaft. The nut is provided with an angular projection |21 which carries the working electrode 58, in the same manner as before with the earlier figures. In assembling the threaded shank and the backing and supporting plate, the lower bent arm with the reentrant termlnal'ls initially bent downwardly to enable the shank be inserted from below into the upper arm, after which the lower arm is bent back substantially to the position indicated in Fig. 8, and the lower terminal is properly placed in the aperture to receive it, and the assembly is complete. If desired, and the flat backing plate' conduces toward it, suitable graduations, as |28, are inscribed on the backing plate column to which an edge of the traveling nut is juxtaposed, so that the setting of the instrument .for the predetermined operating temperature can be read directly against the backing plate. 'I'he assembled plate and its memplate itself laterally Abers is inserted axially into the end of the relatively enlarged tube 20 and rests upon the partition 2|. Then after suitably softening the glass at least one of the upper arms los and m1, and m, Smau indentations are made in the glass to anchor the metallic assembly in place, and the remainder of the closing steps are taken as recited of the earlier tlgures. The upper end of the reduced shank portion ofthe threaded shaft is supplied with the armature, as in the other figures and the arm `is in contact with the short connection 48, and the operation of the device will be clear.

A third point of application of the calibrations is upon the external surface of the glassr tube 20,

vnwarrilv as, at |15, to abut against the side of.

the median partition 2|. and member ||4 terminates ir a short -transverse member H6 reentraniv bent upon itself as at |11. The reentrant portion H1 is apertured as at ||8 and form" a vertical abutment to rest upon the top nf *be nar-tition 2| to support the plate asseme hiv inst rimer-ined. It will be understood that the short rvu-uber IM is nf proper length between *he vertical wall portion H5 andthe free outer wis nf the short arms and ||2 as to llt snugiv between the partition and the inner surface. of the glass tube 20 to anchor the plate. I! desired, the proportions of the arms can be arwhich is advantageous, as the calibrations can be applied, as can those identified as I1 in the earlier figures, after the instrument has been completed instrument can To utilize formed on the traveling nut and juxtaposed to the interior of the glass tube 20. If the vpointer is brightly colored, as by being painted red, or the like, it is perfectly easy to read the setting of the traveling nut, and therefore the operative position of the lower end of the working elec trode 58, relative to the calibrations |28. f

The simplicity, economy and accuracy of the instrument will be clear.

Having thus described my invention, I claim:

1. An adjustable thermostat assembly of glass which comprises a double bored column of glass, a bulb on one end of the column in communication with at least one of the bores therein, a holtion with at least one of the bores therein, a glass c housing on the other end of the column in communication with both bores of the column, and a partition fused to the end of the column between the bores and to the interior of the housing to define spaced pockets communicating with the respective bores of the column mercury in both bores and in said bulb, the mercury in said bores being electrically inter-connected remote from the housing and said pockets and bores being arranged to receive respectively a xed electrode in permanent contact with the mercury in one bore, and a movable electrode arranged for make and break contact with the mercury in the other bore to control a circuit through the thermostat.

3. An adjustable thermostat assembly of glass which comprises a double bored column of glass, a bulb on one end of the column in communication with at least one of the bores therein, a glass housing on the other end of the column in communication with both bores of the column, and a. partition fused to the end of the column between the bores and to the interior of the housing to define spaced pockets communicating with the respective bores of the column, said housing tapering .toward the end of the column to taper said pockets and impart a guiding funnel-like characteristic thereto mercury in both bores and in said bulb, the mercury in said bores being electrically interconnected remote from the housing and said pockets and bores being arranged to receive respectively a fixed electrode in permanent contact with the mercury in one bore, and a movable electrode arranged for make and break contact with the mercury in the other bore to control a circuit through the thermostat, one of said pockets being a reservoir in which to store excess mercury on one side of the partition.

4. An adjustable thermostat assembly of glass which comprises a double bored column of glass, a bulb on one end of the column in communication with at least one of the bores therein, a glass housingon the other end of the column in communication with both bores of the column, a metallic actuating assembly mounted in the housing, comprising a supporting member, a threaded shaft journalled on the member, a threaded nut axially movable on the threaded shaft, an electrode wire carried by the nut\and'having a free end extending into one of the bores of said column, means including mercury in the other of said bores establishing a common electrical ground, electrode connections for leading a power source to the common ground and to the actuating assembly, and means for establishing electrical connection between the working and common electrode. v

5. An adjustable thermostat assembly of glass which comprises a double bored column of glass, a bulb on one end of the column in communication with at least one of the bores therein, a glass housing on the other end of the column in communication with both bores of the column a partition fused to the end of the column between the bores and to the interior of the housing to define spaced pockets communicating with the respective bores of the column, a metallic actuating assembly mounted on said partition and held against unitary Amovement axially of said housing, a metallic electrode connected operatively with the actuating assembly and extending into one of said bores for relative movement therein, a grounding electrode extending from the housing into the other of said bores in said column, mercuryin both bores, and means forming an electrical connection between the mercury in the bores to close the electrical path between the electrodes.

6. An adjustable thermostat assembly of glass which comprises a double bored column of glass, a bulb on one end of the column in communication with at least one of the bores therein, a glass housing on the other end of the column in communication with both bores of the lcolumn a partition fused to the end of the column between the bores and to the interior of the housing to define spaced pockets communicating Witht the respective bores of the column, a metallic actuating assembly mounted on said partition and held against unitary movement axially of said housing, said metallic assembly comprising a preformed unit of a support, a threaded shaft journalled on the support, a nut mounted on the shaft and held against rotation, an armature on the shaft in the housing, a working electrode carried at one end by said nut and extending into one of the bores in said columnj and an external magnetic device juxtaposed to said armature to change the angular position of the latter, and turn the shaft to control axial nut movement, an electrical connection between the bores, and an electrode extending from within the housing into the other of said bores to complete a circuit through the thermostat.

7. An adjustable thermostat comprising an electrode actuating unit including a threaded unit having an axis and the rotation of which unit controls the disposition of an electrode, an armature for the unit comprising a sheet metal element having wings spaced from the axis of the threaded unit.

8. An adjustable thermostat comprising an electrode actuating unit including a threaded unit having an axis and the rotation of which unit controls the disposition of an electrode, an armature for the unit comprising a sheet metal element having wings spaced from the axis of the threaded unit, said wings being joined to the threaded unit by a substantially planar section diametrically extending from the threaded unit and substantially intersecting said axis.

9. An adjustable thermostat comprising an electrode actuating unit including a threaded unit having an axis and the rotation of which unit controls the disposition of an electrode, an armature for the unit comprising a sheet metal element having wings spaced from the axis of the threaded unit, said wings being relatively oppositely extending from a substantially planar section, and the planar section being mounted on the threaded unit.

10. An armature for a threaded unit for an adjustable thermostat comprising an integral sheet metal assembly, the assembly having a symmetrically disposed axial rib and groove portion arranged to embrace a shaft, connecting portions extending laterally outwardly from the rib and groove and wings forming the terminals for the connecting portions each joined at one end to the outer end of its respective connecting portion and extending arcuately in relatively opposite directions generally concentric with the rib and groove portions in spaced relation thereto.

11. An adjustable thermostat comprising a glass bulb, mercury in the bulb, a column of glass mounted on the bulb, said column having two parallel spaced bores comprising respectively a working and a common bore extending longitudinally thereof with one of the bores in communication with the bulb mercury in the common bore, a glass housing fused to the column remote from the bulb, a support mounted in the housing, a rotatable element mounted in the support and including an armature rotatable in the glass housing, an electrode axially adjustable in the working bore, means connecting the electrode and rotatable element for axially adjusting the electrode with rotations of the element. an electrical connecting system in electrical connection at one end with the electrode and at the other extending through the glass housing, a common electrode in the housing extending into the mercury in the common bore, electrical connecting means leading from said common electrode through the glass housing, means establishing electrical connection between the common electrode and the mercury in the working bore, and rotatable means establishing polarized magnetic flux externally of the housing incident upon said armature and so arranged as to rotate the armature and rotatable element as the means is rotated.

12. An adjustable thermostat comprising a' glass bulb,V mercury in the bulb, a column of :x-

glass mounted on the bulb, said column having two parallel spaced bores comprising respectively a working and a common bore extending longitudinally thereof with one of the bores in communication with the bulb. a glass housing fused to the column remote from the bulb, a support mounted in the housing, a rotatable element mounted in the support and including an armature rotatable in the glass housing )an electrode axially adjustable in the working bore, means connecting the electrode and rotatable element for axially adjusting the electrode with rotations of the element, an electrical connecting system in electrical connection at one end with the electrode and at the other extending through the glass housing, a common electrode in the housing extending into the common bore, electrical connecting means leading from said common electrode through the glass housing, means establishing electrical connection between the common electrode and the mercury in the working bore, and rotatable means establishing polarized magnetic iiux externally of the housing incident upon said armature and so arranged as to rotate the armature and rotatable element as the means is rotated, said means establishing electrical connection comprising mercury in the common bore in direct electrical commounication with the mercury in the bulb.

13. An adjustable thermostat comprising a glass bulb, mercury in the bulb, a column of glass mounted on the bulb, said column having two parallel spaced bores comprising respectively a working and a common bore extending longitudinally thereof with one of the bores in communication with the bulb, a glass housing fused to the column remote from the bulb, a support mounted in the housing, a rotatable element mounted in the support and including an armature rotatable in the glass housing, an electrode axially adjustable in the working bore, means connecting the electrode and rotatable element for axially adjusting the electrode with rotations of the element, an electrical connecting system in electrical connection at one end with the electrode and at the other extending through the glass housing, a common electrode in the housing extending into the common bore, electrical connecting means leading from said common electrode through the glass housing` means establishing electrical connection between the common electrode and the mercury in the working bore, and rotatable means establishing polarized magnetic flux externally of the housing incident upon said armature and so arranged as to rotate the armature and rotatable element as the means is rotated, said means establishing electrical connection comprising mercury in the common bore, an electrical connection embedded in the column and in Contact with the mercury in both the common and working bores.

14. An adjustable thermostat comprising a glass bulb, mercury in the bulb, a column of glass mounted on the bulb, said column having two parallel spaced bores comprising respectively a working and a common bore extending longitudinally thereof with one of the bores in communication with the bulb, a glass housing fused to the column remote from the bulb, a support mounted in the housing, a rotatable element mounted in the support and including an armature rotatable in the glass housing, an electrode axially adjustable in the working bore, means connecting the electrode and rotatable element for axially adjusting the electrode with rotations of the element, an electrical connecting system in electrical connection at one end with the electrode and at the other extending through the glass housing, a common electrode in the housing extending into the common bore, electrical connecting means leading from said common electrode through the glass housing, means establishing electrical connection between the common electrode and the mercury in the working bore. and rotatable means establishing polarized magnetic ux externally of the housing incident upon said armature and so arranged as to rotate the armature and rotatable element as the means` is rotated, said means establishing electrical connection comprising mercury in the common bore in communication with the bulb, a pocket being formed in the column in substantial alignment with the common bore. mercury disposed in said pocket, an electrical connector fused in the column and establishing electrical connection between the mercury in the common column and the pocket, and means dening an opening in the pocket into which said common electrode may be inserted to contact with the mercury therein.

l5. An adjustable thermostat comprising a glass bulb, mercury in the bulb, a column of glass mounted on the bulb, said column having two parallel spaced bores comprising respectively a working and a common bore extending longitudinally thereof with one of the bores in communication with the bulb. a glass housing fused to the column remote from the bulb, a support mounted in the housing, a rotatable element mounted in the support and including an armature rotatable in the glass housing, an electrode axially adjustable in the working bore. means connecting the electrode and rotatable element for axially adjusting the electrode with rotations cf the element, an electrical connecting system ananas in electrical connection at one end with the electrode and at the other extending through the glass housing, a common electrode in the housing extending into the common bore, electrical connecting meansleading from s aid common electrode through the glass housing, means comprising mercury establishing electrical connection between the common electrode and the mercury in the working bore, and rotatable means establishing polarized magnetic flux externally of the housing incident upon said armature and so arranged as to rotate the armature and rotatable element as the means is rotated, and calibrations on the thermostat relative to which the axial disposition of the working electrode can be determined.

16. An adjustable thermostat comprising a glass bulb, mercury in the bulb, a column of glass mounted on the bulb, said column having two parallel spaced bores comprising respectively a working and a common bore extending longitudinally thereof with one of the bores in communication with thebulb, a glass housing fused to the column remote from the bulb, a support mounted in the housing, a rotatable element mounted in the support and including an armature rotatable in the glass housing, an electrode axially adjustable in the working bore, means connecting the electrode and rotatable element for axially adjusting the electrode with rotations of the element, an electrical connecting system in electrical connection at one end with the electrode and at the other extending through the glass housing, a common electrode in the housing extending into the common bore, electrical connecting means leading from said common electrode through the glass housing, means establishing electrical connection between the common electrode and the mercury in the workingbore, rotatable means establishing polarized magnetic fiux externally of the housing incident upon said armature and so arrangedas to rotate the armature and rotatable element as the means is rotated, said means for establishing magnetic flux comprising an annular magnet, and means for locking the magnet in a given position relative to the glass housing.

17. An adjustable thermostat comprising ,a glass bulb. mercury in the bulb, a column of glass mounted on the bulb, said column having' two parallel spaced bores comprising respectively a working and a common bore extending longitudinally thereof with one of the bores in communication with the bulb, a glass housing fused to the column remote from the bulb; a support mounted in the housing, a rotatable element mounted in the support and including an armature rotatable in the glass housing, an electrode axially adjustable in the working bore, means connecting the electrode and rotatable element for axially adjusting the electrode with rotations of the element, an electrical connecting system in electrical connection at one end with the electrode and at the other extending through the glass housing, a common electrode in the housing extending into the common bore, electrical connecting means leading from said common electrode through the glass housing, means establishing electrical connection between the common electrode and the mercury in the working bore, rotatable means establishing polarized magnetic nux externally of the housing incident upon said armature and` so arrangedl as to rotate -lthe armature and rotatable element as the means is rotated, said means for establishing magnetic flux comprising an annular magnet, means for locking the magnet in a given position relative to the glass housing. said means comprising a pair of relatively threaded sleeve elements, means for holding one of the elements against movement relative to the thermostat, and surfaces on the respective elements for engaging the magnet.

18. An adjustable thermostat comprising a glass bulb, mercury in the bulb, a column of glass mounted on the bulb, said column having two parallel spaced bores comprising respectively a working and a common bore extending longi.

tudinally thereof with one of the bores in communication with the bulb, a glass housing fused to the column remote from the bulb. a support mounted in the housing, a rotatable element mounted in the support and including an armature rotatable in the glass housing, an electrode axially adjustable in the -worklng bore, means connecting the electrode and rotatable element for axially adjusting the electrode with rotations of the element, an electrical connecting system inf electrical connection at one end with the electrode and at the other extending through the glass housing, a common electrode in the housing extending into the common bore, electrical connecting means leading from said common electrode, through the glass housing, means comprising mercury establishing electrical connection between the common electrode and the mer cury in the working bore, rotatable means establishing polarized magnetic ilux externally of the housing incident upon said armature and so arranged as to rotate the armature and rotatable element as the means is rotated, means for visually determining the exact relative position of the means for establishing the magnetic flux relature rotatable in the glass housing, an electrode l axially adjustable in the working bore, means connecting the electrode and rotatable element for axially adjusting the electrode with rotations of the element, an electrical connecting system in electrical connection at one end with the electrode and at the other extending through the glass housing, a common electrode in the housing extending into the common bore, electrical connecting means leading from said common electrode through the glass housing, means establishing electrical connection between the common electrode and the mercury in the working bore, rotatable means establishing polarized magnetic iiux externally of the housingincident upon said armature and so arranged as to rotate the armature and rotatable element as the means is rotated, means establishing a fixed datum line relative to the glass housing, and said means establishing a magnet flux comprising an annular permanent magnet having calibrations viewable against said datum line to enable minute angular adjustments of the magnet to secure minute axial adjustments of the working electrode.

20. An adjustable thermostat comprising a mercury bulb, a housing, an electrode adjusting mechanism in the housing, a column extending between the bulb and housing as the only structure therebetween, said column containing two relatively parallel bores, of which one is aworking bore, and visual masking means operatively associated with the column and so arranged as to substantially conceal the other one of the said two bores from a given angle of observation thereof while enabling proper visual observation of the said working bore.-

21. An adjustable thermostat assembly of glass which comprises a column of glass having a bore eccentric to the axis thereof, a bulb in communication therewith, a glass housing on the other end of the column in communication with said bore substantially concentric with the axis of said column, an actuating assembly mounted in said housing and carrying a movable electrode eccentric of said housing and in substantially posed substantially concentric with the housing and with said column, an axially movable threaded device mounted on the shaft and having a portion in substantial alignment with said bore to which said electrode is attached, and means for guiding the threaded device for axial movement while substantially precluding rotative mo- .bore substantially concentric with the axis of substantially axial alignment with said bore, said actuating assembly incorporating a rotatable element disposed substantially concentric with the housing and with said column, an axially lmovable threaded device mounted on guide device and a complemental guide means on said device both eccentric to said housing. diametrically spaced from said eccentric electrode. thermostat comprising a bulb for mercury, a hollow housing having uper surface-abutting means Joined substantially rigidly to the elongated member to maintain the xed unit in predeterminedly transversely located position in the housing, and said movable unit connected tosaid electrode.

comprising a 24. An adjustable thermostat a hollow housing having upper bulbfor mercury, and lower ends, a column extending bet bulb and the lower end of the housing as the only structure therebetween, said column having a bore communicating with the housing and with the bulb, an electrode movable into the bore, electrode adjusting mechanism disposed in the housing and comprising a fixed unit and a movable unit, said xed unit comprising an elongated member disposed longitudinally in the housing having at one end at least transverse inner surface-abutting means joined substantially rigidly to the elongated member to maintain the fixed unit in predeterminedly transversely located position in the housing, means formed in the housing to limit the axial movement of the fixed unit to hold it substantially rigid and immovable during motions of the movable unit, and means connecting the movable unit to the electrode.

25. An adjustable thermostat comprising a bulb for mercury, a hollow housing having upper and lower ends, a column extending between the bulb and the lower end` of the housing as the only structure therebetween, said column having a bore communicating with the housing and with the bulb, an electrode movable into the bore, electrode adjusting mechanism disposed in the housing and comprising a ilxed unit and a movable'unit, said fixed unit comprising an elongated member disposed longitudinally in the housing having at one end at least transverse inner surface-abutting means joined substantially rigidly to the elongated member to maintain the fixed unit in predeterminedly transversely located position in the housing, said column having a second bore substantially parallel to the first and forming a channel for a common ground for a circuit controlled by the thermostat.

26. An adjustable thermostat comprising a bulb for mercury, a hollow housing havingupper and lower ends, a column extending between the bulb and the lower end of the housing as the only structure therebetween, said column having a bore communicating with the housing and with the bulb, an electrode movable into the bore, electrode adjusting mechanism disposed in the housing and comprising a ilxed unit and a movable unit, said fixed unit comprising an elongated member having integral spacing means at both ends arranged to cooperate with surfaces in the housing to maintain the elongated member in the housing against any lateral shifts therein. said housing including a relative indentation juxtaposed to the spacing means at one end of the elongated member to preclude axial motion of the fixed unit in at least one direction, said elongated member comprising a guide for the movable unit, and said movable unit being connected to said electrode.- JOHN LEONARD SCHWARTZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,087,150 Hieber et al July 13, 1937 2,108,338 Juchheim Feb. 15, 1938 2,160,404 Hurlburt May 30, 1939 2,264,335 Schwartz Dec. 2, 1941 FOREIGN PATENTS Number Country Date 124,935 Germany Nov. 27, 1901 

